Phase I: Clot formation in the blood vessel (thrombosis) causes a broad range of serious clinical conditions, such as unstable angina, acute myocardial infarction, ischemic stroke, deep vein thrombosis, pulmonary embolism, disseminated intravascular coagulation, and peripheral vascular disease. It is a leading cause of death and disability in the developed countries. Anticoagulant drugs are needed for the short-term treatment of arterial and venous thromboembolic disorders and for the long-term prevention of recurrences. Currently available anticoagulant drugs have various limitations. More efficacious, safer, and easier to use anticoagulants are demanded. The long-term objective of this application is to develop highly effective new anticoagulant drugs to meet the above therapeutic needs. Using genetic engineering technology, EVAS Therapeutics has created a series of recombinant proteins that bind anionic phospholipids with high affinity and potently inhibit membrane-associated coagulation enzyme complexes. As a result, these anticoagulant proteins are site-targeted to thrombus, exceptionally potent, and may achieve superior antithrombotic efficacy with lower risk of systemic bleeding side effects. The main objective of this phase I proposal is to demonstrate the ability of these hybrid proteins to specifically localized on the thrombogenic cells in vitro and to achieve antithrombotic effect in vivo. In addition, small-scale E. coli fermentation and protein production processes will be carried out to supply materials for the in vitro and in vivo studies. The specific aims of this phase I project are to: 1. Establish the binding specificity of the fusion proteins to normal vs. perturbed cells in vitro. Differential binding of the fusion proteins to stimulated vs. resting platelets and endothelial cells will be studied in order to demonstrate the specific binding of the fusion proteins to thrombogenic cells. 2. Demonstrate the antithrombotic efficacies of the fusion proteins and complete the dose response study in a mouse arterial thrombosis model in vivo. A mouse arterial thrombosis model will be used to establish the antithrombotic efficacies of EVAS' anticoagulant molecules. 3. Develop a bioprocess to produce the recombinant fusion proteins for in vitro and in vivo studies. A more efficient fermentation and purification process will be established to provide the needed materials for Phase I research. This process will also lay a foundation for Phase II GLP production of the recombinant proteins.